The goal of this program is to obtain an understanding of some of the mechanisms by which gene expression is modulated in normal eukaryotic cells, and the mechanisms by which this control becomes aberrant following neoplastic transformation. A number of different types of eukaryotic genes will be isolated and characterized and the regulation of these genes in normal and transformed cells will be studied. It may thus be possible to identify specific alterations in the DNA which result in aberrant patterns of gene expression in neoplastic cells. A primary effort will be directed towards the isolation from transformed cells of genes which are responsible for abnormal growth control ("tumor genes").